src/test/ui/impl-trait/equality.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 #![feature(conservative_impl_trait, specialization)]
  12
  13 trait Foo: Copy + ToString {}
  14
  15 impl<T: Copy + ToString> Foo for T {}
  16
  17 fn hide<T: Foo>(x: T) -> impl Foo {
  18     x
  19 }
  20
  21 fn two(x: bool) -> impl Foo {
  22     if x {
  23         return 1_i32;
  24     }
  25     0_u32
  26     //~^ ERROR mismatched types
  27     //~| expected i32, found u32
  28 }
  29
  30 fn sum_to(n: u32) -> impl Foo {
  31     if n == 0 {
  32         0
  33     } else {
  34         n + sum_to(n - 1)
  35         //~^ ERROR no implementation for `u32 + impl Foo`
  36     }
  37 }
  38
  39 trait Leak: Sized {
  40     type T;
  41     fn leak(self) -> Self::T;
  42 }
  43 impl<T> Leak for T {
  44     default type T = ();
  45     default fn leak(self) -> Self::T { panic!() }
  46 }
  47 impl Leak for i32 {
  48     type T = i32;
  49     fn leak(self) -> i32 { self }
  50 }
  51
  52 fn main() {
  53     let _: u32 = hide(0_u32);
  54     //~^ ERROR mismatched types
  55     //~| expected type `u32`
  56     //~| found type `impl Foo`
  57     //~| expected u32, found anonymized type
  58
  59     let _: i32 = Leak::leak(hide(0_i32));
  60     //~^ ERROR mismatched types
  61     //~| expected type `i32`
  62     //~| found type `<impl Foo as Leak>::T`
  63     //~| expected i32, found associated type
  64
  65     let mut x = (hide(0_u32), hide(0_i32));
  66     x = (x.1,
  67     //~^ ERROR mismatched types
  68     //~| expected u32, found i32
  69          x.0);
  70     //~^ ERROR mismatched types
  71     //~| expected i32, found u32
  72 }